We joke a lot about our age but you know, I donít mind turning grey. It makes me look distinguished.

Itís definitely "dis" something…

How about disappearing?

Yeah true… but weíre saving baldness for another episode. As for grey hair, researchers have discovered why our hair is turning grey and itís actually a defense mechanism against disease.

Pretty neat!

Our hair consists of the strands you see called the hair shaft and the root. The root ends in the hair bulb which sits in a sac-like pit in the skin called the follicle. Thatís where the hair grows.

The color of your hair is determined by the amount of melanin in each strand of hair. Red heads and blondes have only a small amount of melanin in their hair. And hair becomes gray when people age because melanin is no longer formed.

Now Japanese researchers may have discovered why. They were looking at the stem cells that produce melanin and what kind of impact DNA damaging agents had on them.

Examples are UV light, radioactivity and X Rays. In mice, these agents caused enough DNA damage to result in premature grey hair.

When DNA is damaged you end up with cell mutations. This causes cells to go into a process called apoptosis where it kills itself so that it will not reproduce.

Thatís normal but with this study, scientists further found that DNA damage forced these melanocyte stem cells to reproduce cells devoid of a nucleus which then die. Eventually none of the cells that produce melanin are left.

Presto — grey hair.

This new discovery, that cells with DNA damage can be eliminated as a whole is how the body protects itself from cells that could become cancerous.

Not a bad tradeoff for graying hair… now if only going bald was as reassuring.

Science Magazine summarized the results of the study that demonstrated that DNA damage can cause hair to grey here and it was also highlighted in National Geographic Magazine here.

Damage Response and Repair Mechanisms is a project carried out by a Consortium of 15 scientific institutions. The participants are located in The Netherlands, Denmark, the United Kingdom, Switzerland, Italy, Germany, Norway, Ireland, and France. Their website contains information for scientists, as well as public science information for non-scientists, including a glossary and their pages include information on DNA Repair and Aging, DNA Repair in Human Disorders, DNA Repair and Cancer as well as DNA Structure.For more information…

For a very simple introduction to DNA, DNA damage and DNA repair, go here.